Method and apparatus for coating paper and the like



METHOD R. s. BRACEWELL 2,130,060

AND APPARATUS FOR COATING PAPER AND THE LIKE Filed Aug. 26, 1955 4 Sheets-Sheet 1 INVENTOR lQ/ ssaz. 6: BRACEWELL ATTORNEYS Sept. 13, 1938. R. s. BRACEWELL 2,130,060

METHOD AND APPARATUS FOR COATING PAPER AND THE LIKE Filed Aug. 26, 1955 4 Sheets-Sheet 2 INVENTOR 51 98544 6 BR4CW4 WwY- 7ml ATTORN EYS p 1938. R. s. BRACEWELL 2,130,060

' METHOD AND APPARATUS FOR COATING PAPER AND THE LIKE Filed Aug. 26, 1935' 4 Sheets-Sheet s 'INVENTOR v {:(PU-SSELL @Bmcswm ATTORNEYS S p 3, 1938. R. s. BRACEWELL 2,130,060

METHOD AND APPARATUS FOR COATING PAPER AND THE LIKE Filed Aug. .26, 1955 4 Sheets-Sheet 4 lN\ IENTOR $188621. 6: Ewan/a4 A TORNEY? Patented Sept. 13, 1938 UNITED STATES METHOD AND APPARATUS FOR COATING PAPER AND THE LIKE Russell S. Bracewell,

Application August 26,

Claims.

This invention relates to coating webs of paper and the like and has for its object the provision of a method and apparatus by which traveling webs may be coated, while traveling at relatively high 5- speeds, in a uniform and satisfactory manner with the degree of reliability necessary for commercial operation.

An important feature of the invention is the provision of a high speed rotating spray roll 1. mounted closely adjacent to but not in contact with said traveling web, and rotated at a suflicient speed to discharge color from its surface by centrifugal action onto said traveling web. The velocity of color discharge for coating the web 18 is such as to disperse the color into the form of a finely divided spray. The surface of the spray roll is so characterized as to cause its discharged color to spread uniformly over the traveling web even when the web is traveling at high speed such as may occur when the web is being coated directly as it emerges from a paper making machine. v

A further feature of the invention is in getting the color onto the high speed spray roll for its subsequent centrifugal discharge therefrom onto the web. To this end I provide means for projecting the color onto the surface of said spray roll in the same general direction as the moving surface of said spray roll preferably by a second roll which also discharges color from its surface by centrifugal action. The rotation of the second or transfer roll is not as fast as that of the spray roll for it serves to give the color only such velocity and direction of discharge as will easily transfer said color to the high speed spray roll. In this manner the velocity of the color is progressively accelerated up to the point of its final coating discharge onto the web.

A still further feature of the invention is the means for taking up color from a reservoir and feeding it to the second or transfer roll. This is accomplished preferably by a color take-up roll dipping into a reservoir of color and having its surface adjacent to but not in contact with the transfer roll. The adjacent surfaces of said rolls are specially constructed for an easily controlled flow of color from one to the other as will be later described.

Other and further objects will be apparent from the following specification andclaims.

In the accompanying drawings, Fig. 1 is a side elevational view of a coating machine embodying my invention;

Fig. 2 is a fragmentary end sectional view sub- 5Q stantially on line 2-2 of Fig. 1;

South Hadley, Mass.

1935, Serial No. 37,844

Fig. 3 is a transverse sectional view of the suction box which supports the paper web during its coating operation; I

Fig. 4 is a fragmentary elevational view showing the general relation of the color, transfer and 5 spraying rolls; I

Fig. 5 is a diagrammatic view showing my invention applied to the coating of paper as part of the manufacturing process;

Fig. 6 is a diagrammatic view showing an arrangement for coating both sides of the paper;

Fig. 7 is a fragmentary view showing a modified form of surface grooving for the spray roll;

Fig. 8 is a diagrammatic side view of a modified arrangement in which a second auxiliary spray roll is used; and

Fig. 9 is a fragmentary plan view of the spray rolls of the arrangement shown in Fig. 8.

Referring to Figs. 1 and 2, reference character I indicates the frame of the machine which supports a color reservoir 2. The reservoir, if desired may be provided with an agitating means 3 driven by any suitable means not shown. A color roll 5 journaled in bearing 6 rotates in the color bath in the reservoir, to pick up color therefrom. Roll 5 is provided throughout its length with circumferential grooves 9 which are preferably narrow and close together. These grooves are straight and concentric as distinguished from a spiral groove. Twelve grooves to the inch with a depth of one-eighth of an inch gives satisfactory results but the number and dimensions may be varied within reasonable limits. As it is desirable to confine the width of the color band picked up by roll 5 to substantially the width of the web to be coated, scrapers or doctors I, provided with pro- Jections fitting into the grooves 9 (see Fig. 4) are adjustably mounted on rods 8 adjacent the end portions of roll 5.

Positioned above roll 5 is a transfer roll I0 journaled in bearings l I. Transfer roll I0 is similarly circumferentially grooved as at 12 to correspond to roll 5, the dimensions of the grooves of roll l0 being such that the flanges M which separate the grooves may enter grooves 9 of roll 5 without actually contacting the walls of the latter grooves.

The color is transferred by roll ID to a spray roll l5 positioned to just clear roll l0 and journaled in bearings I 6. Roll I5 is provided on its surface with a spiral groove l8. The groove l8 may correspond in dimensions to grooves I! of roll l0 although the actual dimensions are not critical. In the form illustrated in Figs. 2 and 4 the spiral groove has a lead approximately equal to the spacing of cgrooves I2. Obviously if the lead is increased the form and dimensions of the grooves must be changed to correspond or a plurality of spiral grooves must be used. Guards I9 are mounted at the sides of rolls I0 and I5 to confine the spray of color during the coating operation as later described. A partition wall I9 extends inwardly from one side of the guard. Ii:- up to a point close to spray roll I5 as shown in dotted lines in Fig. 1, so as to confine the downward discharge from spray roll I5. It will be appreciated that the high speed rotation of spray roll I5 will also set -up a considerable current of air in the direction of its peripheral travel due to the surface friction of said periphery with respect to the air through which it travels, and that the partition wall I8 positioned as shown acts as a baifle to prevent this peripheral air current from unduly disturb.- ing the projection of the color from the transfer roll III to said spray roll I5.

The web to be coated, such as a web of paper 20, is led into close proximity to but not in contact with the spray roll I5 and is supported in its passage over roll I5 by a suction box 2|, adjustably mounted by means of screws I0 on the main frame of the device. Screws I0 may be conveniently operated by hand wheels II.

As best shown in Figs. 2 and 3 the bottom of the main portion of box 2I is formed by members 22 extending inwardly from the sides to leave an opening 23 extending the full length of the box and of a width no greater than the minimum width of the web to be coated. Positioned beneath members 22 are a plurality of rolls 24 rotatably mounted in bearings 25 and adapted to be rotated at web speed by pulley 25, or the like, from a suitable source of power, not shown. A pair of rods 21 (see Fig. 1) extending transversely of the machine, between and parallel to the members 22 and rolls 24, slidably support deckles 28. The upper edges of deckles 28 slide on the under surface of members 22 and the lower portion of the deckles are provided with projections 29 (Fig. 1) extending downwardly between rolls 24 with their side edges conforming to the curvature of the rolls and with their lower edges in proximity to the web traveling against rolls 24. As will be obvious deckles 28 shut off the space at the ends of rolls 24 making the suction between that portion of the rolls intermediate the deckles efiective I to hold the web against the rolls.

The deckles are adapted to be adjusted on their supporting rods, to position them, as shown in Figs. 2 and 3, adjacent the edges of the web 20, by means of shafts 30 journaled in brackets 3| and threaded into the deckles at 32. Shafts 30 are provided with hand wheels 33 by which the shafts 30 may be rotated to advance or retract the deckles to desired position.

Suction is supplied to box 2I from a suitable source, not shown, through conduit 34.

Referring to Fig. 1, the web 20 is drawn from I a suitable supply roll 40 over a guide roll 4I, be-

neath a guide roll 42, beneath suction box 2|, just described, and around guide rolls 43 and 44 to a drying means and wind-up mechanism not shown. As will be clear from Figs. 1 and 2, the web as it travels beneath suction box 2| is brought into close proximity with the surface of roll I5.

Rolls 5, III and I5 are driven in the direction of the arrows in Fig. 1 by any suitable means not shown. Roll I5 is preferably driven at a speed of the order of 3800 R. P. M. and roll III at a speed of the order of 1100 R. P. M. and the speeds 0 these rolls need not be changed for norma changes in the speed of the web. The speed of roll 5 is varied with the speed of web travel and its speed controls the thickness of the coating applied. Roll 5 may therefore conveniently be.-

driven from the same source of power as the web feeding means through cone pulleys or other speed regulating devices. For a speed of web travel of around 500 feet per minute the speed of roll 5 should be of the order of 58 R. P. M. to give a normal coating. For the speeds given, diameters of 5 inches for roll 5, 35 inches for roll I0, and 10% inches for roll I5 give satisfactory resuits.

In operation color is picked up in the grooves 9 of roll 5 from which it is taken by the flanges I4 of roll I0. Roll III rotates at a speed sufllcient to discharge the color onto roll I5 by centrifugal action. The color is discharged from roll III in narrow bands due to the circumferential grooving of the roll I 0 but the spiral grooving of roll I 5 spreads these bands transversely and the color is discharged by a centrifugal action from the surface of roll I5 as a smooth even coating onto the traveling web, which is held in proper position by the suction box as it passes over roll I5.

It will be understood that the drawings do not attempt to show the width and depth of the grooves, or the spacing of the rolls with respect to each other and the web, to scale. In the preferred practice rolls I0 and I5 just clear each other and roll I5 just clears the web, but the groove dimensions and roll and web spacing, as well as roll diameters and speeds, may be varied as conditions may require. Preferably the grooves are very narrow and close together.

As shown only the. bearings II of roll III are made adjustable, but all the bearings may be made similarly adjustable if desired.

In Fig. 7 a different form of surface grooving for roll I5 is shown comprising a plurality of oppositely directed spiral grooves 80 and UL In Figs. 8 and 9 is shown diagrammatically a modified arrangement in which an additional or auxiliary spray roll 10 is mounted behind the main spray roll I5. The purpose of roll I0 is to catch color which is sprayed to the rear of the principal roll and in turn spray it on the web. The two spray rolls I5 and I0 run in the same direction, that is the top surfaces of both run in the direction of the travel of the web being coated. Roll I0 is similar to roll I5 in that it just clears the web as shown. The addition of roll -I0 assists in giving a uniform color coating to the web. Roll III is provided with grooves II which grooves are similar in form to grooves I8 of roll I5. As shown in Fig. 9, these grooves II and I8 preferably run in the same direction and are substantially of the same pitch.

One important advantage resulting from the high speeds at which webs can be coated by my device is that paper webs may be coated directly as they are delivered from a paper making machine substantially as a part of the paper making operation. In Fig. 5 I have shown diagrammatically one arrangement which such an installation may take. In said figure 50 indicates the delivery end of a paper making machine from which the web of paper 5| is led around a conventional drying drum 52. As the web passes around drum 52 one side is coated by a coating unit A made according to my invention as above described, the rolls 5, I0 and I5 being diagrammatically shown by the circles so designated. From drum 52 the web is reversed around guide rails 53 and carried around a second drying drum 55 where the other side of the web is coated by a second coating unit B. From drying drum 55 the web travels around guide rolls 56 to any further desired finishing device, such as the stack calender 58, and thence to a wind-up 59.

A different arrangement for coating both sides of a web is shown diagrammatically in Fig. 6 in which the web 60 is led around a guide roll 6| between opposed coating units C and D which simultaneously coat both sides of the web. The web is then passed through a drying chamber 62 in which, guided by rolls 63, it passes between drying jets of warm air as indicated at 64. From the drying chamber the web is passed around guide rolls 65 to a wind-up 66.

It will be understood that the term color" as used in this specification and the claims includes any of the coating materials usually employed for coating purposes, and that the method and apparatus of this invention may be used for spraying material in the form of a fine powder or dust, such as gold, aluminum or mica, in the same manner as liquid materials, the webs to which powdered material is applied being first sized or otherwise treated to cause adherence thereto of the powdered material.

I claim:

1. A device for coating webs of paper and the like which comprises a roll for taking up color from a color supply, said take-up roll being formed with circumferential grooves, a transfer roll having circumferential ribs running in the grooves of the take-up roll and receiving color therefrom, a spirally grooved roll slightly spaced from the transfer roll to receive color therefrom by centrifugal action and means to present the surface to be coated in close proximity to the spirally grooved roll to receive color therefrom by centrifugal action.

2. A device for coating webs of paper or the like which comprises a roll for taking up color from a color supply, said take-up roll being formed with narrow closely spaced circumferential grooves, a transfer roll having circumferential ribs running in the grooves of the take-up roll and receiving color therefrom, a spraying roll positioned in close proximity to the transfer roll to receive color therefrom by centrifugal action, said spraying roll having its surface spirally grooved to spread the color axially along the spraying roll and discharge it onto the surface to be coated.

3. A device for coating webs of paper and the like which comprises a spraying roll having its surface spirally grooved, means to supply color to said roll and means to direct the web to be coated past said roll in close proximity to the surface thereof.

4. A device for coating webs of paper or the like which comprises a roll for taking up color from a color supply, said take-up roll being formed with narrow closely spaced circumferential grooves, a transfer roll having circumferential ribs running in the grooves of the take-up roll and receiving color therefrom, a spraying roll positioned in close proximity to the transfer roll to receive color therefrom by centrifugal action, said spraying roll having its surface spirally grooved to spread the color axially along the spraying roll and means comprising a suction box to present the web to be coated in close proximity to the spraying roll.

5. A device for coating webs of paper and the like which comprises a spraying roll having its surface spirally grooved, means to supply color to said roll, and a suction box having one sidev formed of a plurality of closely spaced rolls over which the web'passes in close proximity to the spirally grooved spraying roll.

6. A devicefor coating webs of paper and the like which comprises a spraying roll having its surface spirally grooved, means to supply color to said roll, a suction box having one side formed of a plurality of closely spaced rolls over which the web passes in close proximity to the spirally grooved spraying roll, the sides of said box having portions extending between the web engaging rolls, and means to adjust said portions toward and from each other to vary the width of the suction area effective between the rolls.

7. An apparatus for coating a traveling web with color comprising a high speed spray roll mounted closely adjacent to but not in contact with said web, said spray roll having a spirally grooved surface adapted to receive color and being rotated at sufficient speed to discharge color therefrom by centrifugal action onto said web in the form of a finely divided spray, means for delivering color to said'spray roll by projecting the color against the rotating surface of said spray roll.

8. An apparatus for coating a traveling web with color comprising a high speed spray rollv mounted closely adjacent to but not in contact with said web, said spray roll being rotated at sufficient speed to dischargecolor therefrom by centrifugal action onto said web in the form of a finely divided spray, a second roll mounted closely adjacent to but not in contact with said sprayroll and acting to deliver color by centrifugal action onto said spray roll, the rotation of said second roll being slower than said spray roll and with the adjacent surfaces thereof moving in the same general direction and means for supplying color to the surface of said second roll.

9. An apparatus for coating a traveling web with color comprising a high speed spray roll mounted closely adjacent to but not in contact with said web, said spray roll being rotated at suflicient speed to discharge color therefrom by centrifugal action onto said web in the form of a finelydivided spray, a second roll mounted closely adjacent to but not in contact with said. spray roll and acting to deliver color by centrifugal action onto said spray roll, the rotation of said second roll being slower than said spray roll and with the adjacent surfaces thereof moving in the same general direction, and a third roll for taking up color from a reservoir and transferring said color to said second named roll, the surface of said take-up roll being closely adjacent to but not in contact with said second roll.

10. An apparatus for coating a traveling web with color, comprising a high speed spray roll mounted with its axis of rotation extended transversely to the direction of travel of said web and having its peripheral surface in closely adjacent tangential relation to but not in contact with said web, means for rotating said spray roll at sufficient speed to discharge color from its peripheral surface by centrifugal action onto said web in the form of a finely divided spray, a color supply for said spray roll comprising means for projecting color against one peripheral portion of said rotating spray roll simultaneously with the discharge of color to the web from another peripheral portion of said spray roll.

11. An apparatus for coating a traveling web with color, comprising a high speed spray roll mounted with its axis of rotation extended transversely to the direction of travel of said web and having its peripheral surface in closely adjacent tangential relation to but not in contact with said web, means for rotating said spray roll at sufficient speed to. discharge color from its peripheral surface by centrifugal action onto said web inthe form of a finely divided spray, a color supply for said spray roll comprising means for projecting color against one peripheral portion of said rotating spray roll simultaneously with the discharge of color to the web from another v peripheral portion of said spray roll, said color being projected onto said spray roll at a velocity less than the peripheral speed of said spray roll and in the same general direction as the peripheral'movement thereof.

12. An apparatus for coating a traveling web with color, comprising a high speed spray roll mounted with its axis of rotation extended transversely to the direction of travel of said web and having its peripheral surface in closely adjacent tangential relation to but not in contact with said web, means for rotating said spray roll at suflicient speed to discharge color from its peripheral surface by centrifugal action onto said web in the form of a finely divided spray, a color supply for said spray roll comprising means for projecting color against one peripheral portion of said rotating spray roll simultaneously with the discharge of color to the web from another peripheral portion of said spray roll and. a battle partition extending toward and away from the peripheral surface of said spray roll and positioned adjacent that portion of said peripheral surface upon which the color is received from said projecting means.

13. The method of coating a traveling web with color which comprises the step of operating a centrifugally acting discharge surface at a speed sumcient to discharge color therefrom onto said traveling web in the form of a finely divided spray, and the step of supplying color to said centrifugally acting discharge surface by projecting the color thereto at a velocity less than the discharging velocity of said surface, and in the same direction of travel as said discharging surface. a

14. The method of coating a traveling web with color which comprises the step of operating a centrifugally acting discharge surface at a speed sufficient to discharge color therefrom onto said traveling web in the form of a finely divided spray, and the step of supplying color to said centrifugally acting discharge surface by projecting the color thereto from a second centrifugally acting discharge surface having a velocity of discharge less than the velocity of discharge of said first named surface.

15. The method of coating a traveling web with color which comprises the step of operating a centrifugally acting discharge surface at a speed sufllcient to discharge color therefrom onto said traveling web in the form of a finely divided spray, the step of supplying color to said centrifugally acting discharge surface by projecting the color thereto from a second centrifugally acting discharge surface having a velocity of discharge less than the velocity of discharge of said first named surface, and the stepof feeding a supply of color into continuous contact with the surface of said second named centrifugally acting discharge surface.

RUSSELL S. BRACEWELL. 

